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Using Expanded Form
“Roberto's rectangle helps explain the way I did the problem,” said Shannon. “I broke each number into tens and ones, too, but I didn't draw rectangles.” After writing the numbers in expanded form, Shannon multiplies each part by every other part.
- Discuss with a partner how each number in Shannon's expanded-form method fits into the partitions of the rectangular model Roberto drew.
Irma disagrees with Shannon's expanded-form method. Irma explains her reasoning this way:
- Is Irma's answer reasonable? Does her method work? Explain your reasoning.
- Which parts of Roberto's rectangle are not included in Irma's method?
- What is the correct answer to 23 52?